Pump device for a container for liquid, pasty or foamable cleansing and skin care preparations

ABSTRACT

The subject matter of the invention is a pump device for a container for liquid, pasty or foamable skin care preparations, e.g. for liquid soaps, disinfectants, skin protection pastes or creams, wherein the pump device comprises a conically tapering bellows, wherein the bellows exhibits several bellows elements each having a different diameter, wherein at least one smaller bellows element can be pushed into an adjacent larger bellows element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority of German Patent Applications DE 10 2011 014 169.3-16 filed Mar. 16, 2011; DE 20 2011 100 895.2 filed May 19, 2011; and DE 20 2011 105 790.2 filed Sep. 16, 2011, the contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a pump device for a container for liquid, pasty or foamable skin care preparations, e.g. for liquid soaps, disinfectants, skin protection pastes or creams, wherein the pump device comprises a conically tapering bellows, wherein the bellows exhibits several bellows elements each having a different diameter. The skin cleansing preparations can in this connection also contain abrasive bodies.

BACKGROUND OF THE INVENTION

Pump devices of the type initially mentioned are sufficiently well known from the prior art. These pump devices are also referred to as suction pumps and in particular as bellows pumps. They are arranged on a container, wherein the container for example holds a liquid soap and is used in a dispensing device which for example can be mounted on a wall next to a washbasin. By compressing the pump device, for example a bellows pump, the quantity of liquid present in the bellows pump is delivered; wherein then during the return movement of the bellows of the pump device liquid from the container is drawn into the bellows chamber formed by the bellows. Such a pump device is for example known from DE 20 2009 006 603.7 U1.

A pump device arranged on a container is also described in WO 2009/103583, said pump device being accommodated in a dispenser housing. The pump device comprises a laterally projecting protrusion arranged on the outlet-side which, as is known in principle, is held by a so-called “catcher clamp”. The “catcher clamp” of the dispensing device provides for the pump movement of the bellows in the event of the actuation of a lever pivotably connected to it. The introduction of the protrusion of the bellows chamber into the “catcher clamp” takes place against a lateral resistance, since the “catcher clamps” are somewhat pressed apart in the insertion operation, as a result of which the bellows laterally yield. Then the protrusion must be manually placed into the “catcher clamp”.

The pump device in accordance with WO 2009/103583 A1 comprises a cylindrical bellows for formation of the bellows chamber, wherein guide means are provided laterally to the bellows in order to ensure that in the case of the insertion of the container including the pump device into the dispenser housing the bellows cannot give way laterally. The proposed construction is very elaborate and thus also expensive, which in particular is justified by the fact that the bellows exhibits the lateral guide means in the form of rods which must be fastened to both ends of the bellows.

The bellows according to the prior art is constructed in the manner of a pair of bellows, wherein the folds of the pair of bellows run twisted in the manner of a spiral. Such bellows are elaborate in production.

In addition, the following is to be pointed out: Dispensing devices of different manufacturers are in use. However, these dispensing devices possess a holder for the container, wherein the so-called “catcher clamp” is provided spaced in axial position to the holder. The distance from the catcher clamp to the holder for the container varies. That is, in order to insert a container with a fixed pump device into the dispensing device it can be necessary that at least during the insertion operation the bellows of the pump device where applicable must be held squeezed together. This is extremely inconvenient, in particular when additionally the lateral yielding is supposed to be prevented. In addition, consider the fact that the bellows chamber formed by the bellows can be filled with liquid.

Thus the problem addressed by the invention consists in providing a pump device of the type initially mentioned which can be produced by simple and reasonably priced injection molds, thus in particular does not exhibit any undercuts, which in addition exhibits an increased stability transversely to the longitudinal axis in order to prevent an outward swiveling of the bellows in the case of the insertion into the dispensing device.

BRIEF DESCRIPTION OF THE INVENTION

To solve this problem in accordance with the invention it is proposed that the bellows as a conical structure exhibits several bellows elements of differing diameter, wherein at least one smaller bellows element can be pushed into an adjacent larger bellows element. The bellows, which forms a bellows chamber, is constructed to be conically tapering on the basis of the bellows elements adjoining one another of differing diameters. Through the conicity the bellows receives an increased rigidity transversely to the longitudinal axis of the bellows. From the conicity of the bellows and the feature that the individual bellows elements can be pushed into one another, it follows that the bellows does not exhibit any undercuts, so that such a bellows can be economically produced using simple tools. In addition, due to the fact that according to a special feature of the invention the individual bellows elements can be locked into position with one another in compressed state, it becomes possible to compress the bellows of the pump device to a length which corresponds approximately to the distance from the holding fixture for the container to the “catcher clamp.” That means that for the insertion of the container with the pump device the bellows of the pump device remains in pushed in or at least partially pushed in state at least until the container is inserted into the dispensing device.

In order to prevent the bellows elements of the bellows from getting out of control, i.e. to prevent a pushing in of the individual bellows elements beyond their dead center position, provision is made that the base element and/or the wall element are constructed diamond-shaped, square or rectangular in cross-section. In particular in this connection the film hinge in extended state of the bellows connects the base and wall element via the shortest distance between base and wall element. It is additionally advantageous in this connection if the cross-section of the annular base element corresponds approximately to the radial distance between two wall elements, thus in particular the cross-section is not smaller, but rather larger; this measure likewise prevents the “bellows elements of the bellows from getting out of control.” During compression the following then happens: The respective annular base element swivels by circa 90° and abuts with one of its surfaces the upper and lower wall element. The individual bellows element remains in this position, but it can be transferred back to the extended position with a minimum expenditure of force. In this connection there is no risk that the bellows elements will be compressed beyond their dead center position with normal expenditure of force, because this could result in damage to the film hinges.

Advantageous embodiments and features of the invention arise from the subsidiary claims.

For example, in particular provision is made that the bellows elements exhibit a cascading course in section. In particular from this it is clear that the bellows produced in such manner does not exhibit any undercuts. In particular provision is further made in this connection that each bellows element exhibits an annular base element as well as an annular wall element connected by an annular film hinge, wherein in particular the width of the annular base element is greater than the total of the thickness of the annular base element and of the annular wall element. From this it is clear that in the compressing of the bellows, in which case the bellows elements that are smaller in diameter lock into place into the larger annular wall element above swiveling around the respective film hinge, the individual bellows elements remain in this position until the bellows chamber is pulled apart again. This locking operation in the case of the pushing in of the smaller bellows element into the larger bellows element located above becomes especially clear when the annular base element is at an angle of >90° but <180° to the annular wall element in the initial state of the bellows, wherein then, when in the event of pushing in the annular base element is pushed beyond a dead center, wherein after passing the dead center the annular base element comes to rest about parallel to the annular wall element located above, wherein at least partially the smaller annular wall element, or in other words the annular wall element located beneath is likewise parallel to the annular wall element located above.

In this respect the bellows can for example be completely compressed, which in addition to the actual pumping operation if applicable also offers advantages in the case of transportation, to be precise insofar as then the pump device only takes up relatively little space, or it is compressed in the state in which it is placed on the container by precisely the amount which is necessary to facilitate the insertion of the container together with the pump device into the dispensing device in simple fashion, as has already been described.

The pump device comprises an inlet and outlet valve. The inlet valve is located on the pump device in the region of the transition to the container, while the outlet valve is arranged on the lower, conically tapering end of the pump device or of the bellows.

In this connection provision is made that according to a first embodiment the outlet valve is arranged on the bellows as a pivoting valve flap, to be precise in the region of a cylindrical outlet connector. In particular the valve flap is fastened by a web in the region of the valve seat on the outlet support of the bellows.

According to an additional feature of the invention in particular an overrun of liquid from the outlet valve in the bellows chamber of the bellows in the case of non-usage should be prevented. According to a feature of the invention this is prevented by having the valve disk of the outlet valve held pressed against the valve seat under the load of a spring element. In this connection according to an especially advantageous embodiment provision is made that an outlet spout can be plugged onto the outlet connector, wherein the outlet spout exhibits the spring element, in particular constructed in the manner of a spiral spring, wherein the spring element in plugged state of the outlet spout abuts on the valve disk and the valve disk is held pressed against the valve seat. From this it is clear that the valve disk in the case of the compression of the bellows for the purpose of delivery of the preparation in the bellows chamber of the bellows, e.g. a liquid soap is deflected downward against the force of the spring element and with this is opened.

The spring element constructed as a spiral spring located in the outlet spout is characterized by the fact that the spiral spring only possesses a single gear, so that the spring element does not exhibit an undercut.

According to a second embodiment the outlet valve is constructed as a disk valve and arranged liquid-tight in the outlet connector of the bellows. This disk valve in particular features a valve body, wherein the valve body receives a valve disk through a neck at a distance from the valve body, said valve disk abutting on the outlet connector in radially moveable fashion. From this it is clear that when the bellows is compressed the valve disk forms a radial distance to the outlet connector for the passage for example of the liquid soap. In this connection in addition in particular provision is made that the valve disk exhibits a circumferential rotating sealing lip which is arranged on the neck running in the direction of the neck. That means that the sealing lip of the valve disk runs obliquely, in particular at an angle of circa 45° cm to the connection nozzle. Through the selection of the inclination of the sealing lip consequently the selection of the work angle of the sealing lip to the wall of the connection nozzle support, the force necessary so that in the compression of the bellows the sealing lip swivels radially inward, thus to the neck can be influenced, and hence offers a passage for the medium located in the bellows chamber. It also turns out that in the oblique alignment of the sealing lip to the inside wall of the connection nozzle in the initial state of the bellows the sealing lip abuts with a sufficiently high pressure on the inside wall of the connection nozzle in order to prevent an unintended overrun of the medium located in the bellows chamber of the bellows, for example a liquid soap.

In this connection it turns out to be advantageous if in the transition from the neck to the valve disk a tangential circumferential groove is provided in order to facilitate the swiveling of the sealing lips for release of the passage for e.g. a hand wash paste.

In addition the neck of the valve body exhibits an opening which is connected to an outlet spout of the valve body so that in the case of the compression of the bellows the medium in the bellows chamber that is displaced in this connection can enter through the radially circumferential gap between the inside wall of the connection nozzle and the sealing lip into the opening of the valve body, from where it reaches the outside through the outlet spout.

According to another feature of the invention provision is made that the valve body can be received by means of clipping by connection nozzle, wherein as a result the assembly is facilitated. In addition the valve body exhibits a protrusion which is can be held by the catcher clamp of the dispensing device, which has already been described.

The pump device comprises in addition a cover on the inlet side which can be received by the bellows, wherein the cover bears the inlet valve. The inlet and outlet valves work in reverse. That means that when the inlet valve is closed during the compressing of the bellows, in contrast to this the outlet valve is opened, since the valve disk is transferred against the force of the spring element in open position by the pressure of the preparation due to the decrease of the volume of the bellows chamber. The inlet valve further comprises a valve disk which is held pressed against the valve seat in the cover by a spring element in order to relieve the bellows and with it also the outlet valve from the pressure of the liquid column of the preparation in the container.

It has already been pointed out elsewhere that the container holds liquid, pasty or also foamable cleansing and skin care preparations. In particular in the case of the pasty masses in the container, that e.g. skin protection pastes or creams a decomposition of the solid from the liquid portion of the pasty mass was detected in the pumping. In the course of such investigations it turns out that the reason for this lies in too low of vacuum in the pumping operation. To increase the vacuum according to a special feature of the invention it is in this respect proposed that the valve cover exhibit a valve ceiling which receives the inlet valve and which in the direction of the bellows is discharged in cascading manner into the bellows chamber formed by the bellows. Through the minimization of the dead space the vacuum is increased in the pumping operation.

A further measure also serves the objective of the lessening of the dead space, said measure consisting in providing an annular circumferential nose as packing on the underside of the valve ceiling, thus on the side facing the bellows. This nose is constructed in such a way that it does not collide with the individual bellows elements in the pumping operation. This is achieved in particular by constructing the nose approximately triangle-shaped in cross-section, wherein the lateral surface of the triangular-shaped nose facing the wall of the bellows is aligned at an angle to the center of the bellows, that is, the triangle-shaped nose points with the tip to the direction of the bellows. The nose additionally exhibits a radial distance to the valve disk of the inlet valve, which means that through this circumferential annular nose, the e.g. pasty mass is directly adjusted during the pumping to the center of the bellows chamber, said chamber being formed by the bellows.

The pump device or the individual parts of the pump device such as in particular the bellows, outlet connector and cover can be manufactured out of plastic, e.g. PE in the injection molding method.

The invention will be explained more closely in the following by way of example with the help of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the pump device in section in a lateral view;

FIG. 1 a shows the detail “x” from FIG. 1;

FIG. 1 b shows the detail “x” from FIG. 1 in the extended position of the bellows, wherein however the design of the base and wall elements has been changed in comparison to the representation according to FIG. 1 a;

FIG. 1 c shows the bellows according to FIG. 1 b in compressed state;

FIG. 2 shows a view according to the line II-II from FIG. 1;

FIG. 3 shows a view according to FIG. 1, wherein however the bellows is compressed;

FIG. 4 shows another embodiment of the pump device with an outlet valve as a disk valve;

FIG. 5 shows another embodiment of the pump device according to FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

Taken as a whole the pump device exhibits the reference number 1. The pump device 1 comprises the bellows labeled 10, wherein the bellows has the outlet connector 20 on the outlet side end. The outlet connector 20, which is cylindrical in design, receives the outlet spout labeled 30. The outlet connector 20 shows the outlet valve marked 25, wherein the outlet valve 25 comprises a valve disk 26, which is connected by a web 27 to the outlet connector 20. The outlet spout 30 comprises a protrusion 31 running perpendicular to the longitudinal axis of the pump device, wherein the protrusion 31 can be held by the previously described “catcher clamp”. The outlet spout 30 in addition shows the spring element 35 constructed as a spiral spring, said spring element pressing from below, that is against the direction of the outlet against the valve disk 26, and hence presses the valve disk against the valve seat 28.

The bellows 10, which forms the bellows chamber 10 a, possesses on the upper end a threaded cover labeled 40. The threaded cover 40 receives the threaded connector 51 of the schematically represented container 50. The threaded cover 40 exhibits a circular circumferential recess 42 which receives a valve cover labeled 60. The inlet valve labeled 70 as a whole is arranged on the valve cover 60 on the valve ceiling 61 on the underside of the valve ceiling, wherein the inlet valve comprises a valve disk 71, wherein the valve disk 71 possesses a knob 72 facing the direction of the container 50, said knob being positively gripped by a spring clip 63. The spring clip 63 ensures through the connection to the knob 72 that the valve disk 71 of the inlet valve 70 is pressed against the valve seat 65 on the underside of the valve ceiling 61. The valve cover 60 additionally exhibits a wall 66 as well as a circumferential base 67 which stands on the base 41 of the threaded cover. That is, when the threaded cover 40 is screwed onto the threaded connector 51 of the container 50, then the cover 60 is held in the recess 42 of the threaded cover 40.

The design of the bellows 10 will be described more closely in the following with the help of FIG. 1, FIG. 1 a, and FIG. 3. The bellows 10 as a conical structure exhibits several bellows elements 11 which proceed in cascading manner, wherein such a bellows element 11 comprises an annular wall element 12 and an annular base element 14 connected to said annular wall element via a film hinge 13. The wall element 12 and the base element 14 are at an overextended angle a of roughly 110° to one another. The length of the annular base element 14 is selected in such a way that the sum of the thickness of the annular base element and the thickness of the annular wall element 12 corresponds to the width of the annular base element, so that in the compression of the bellows 10, as shown in FIG. 3, a lower annular wall element 12 as well as an annular floor element come to rest at the interior of the annular wall element 12 located above. That is, the individual bellows elements 11 interlock in this connection when the bellows 10 of the pump device 1 is compressed, as is the case e.g. in a pump operation. An at least partial compression of the bellows can however also be necessary in the insertion of the container with the pump device into the dispensing device when the lateral protrusion is supposed to be held by the “catcher clamp”.

In the design of the bellows according to FIG. 3 it is possible to compress this bellows 10 beyond its dead center position, that is, to compress it even more than is the case in FIG. 3. This can result in damage to the bellows and in particular here to the film hinge 13. In addition the bellows 10 can only be transferred back to the extended position with increased expenditure of force. In order to prevent the individual bellows elements of the bellows from “getting out of control” 10 provision is made in accordance with the representations in FIG. 1 b and FIG. 1 c, to construct at least the base element 14, preferably however also the wall element 12 as a ring in cross-section diamond-shaped, square or rectangular, to connect the base and wall elements via the shortest distance through the annular film hinge and to select the cross-section of the base element 14 in such a way that said cross-section corresponds roughly to the radial distance of two wall elements 12 to one another in compressed state of the bellows elements. Thus in compressed state the wall elements support themselves via base elements, which has the result that the individual bellows elements 11 can not be compressed beyond their dead center position as shown in FIG. 1 c.

The operation of the pump device 1 with an outlet valve according to a first variant presents itself in the following manner:

The container 50 is filled with a liquid, e.g. soap. The liquid column of the soap in the container presses on the upper side of the valve disk 71. The spring clip 63 is dimensioned such that the valve disk does not release the valve seat 65 solely through the liquid column on the valve disk. If the bellows 10 is now compressed, then the soap located in the bellows chamber 10 a is conducted outward through the outlet spout 30. In this connection, due to the pressure in the interior of the bellows chamber 1-a the valve disk 26 is swiveled against the force of the spring element 35 around the web 27 in the direction of the outlet spout 30. If the extension of the bellows 10 takes place on the other hand, then as a result of to the vacuum arising in the bellows chamber 10 the valve disk 71 is withdrawn from the valve seat 65, with the consequence that liquid influxes from the container 50 into the bellows chamber 10. In this connection the valve disk 26 abuts the valve seat 28.

Essential in this connection is the fact that the effective area of the valve disk 71 on the upper side (arrow 71 a) is smaller than on the underside (arrow 71 b). This has the consequence that in the filling of the bellows chamber 10 a a relatively large area is available for the vacuum arising in the bellows chamber 10 a, in order to bring the valve disk to the open position. The area of the valve disk 71 on the upper side (arrow 71 a) is dimensioned such that in the case of a pending liquid column the spring clip 63 is able to hold the valve disk in the closed position so that no additional pressure is exerted on the liquid column located in the bellows chamber, with the consequence that the outlet valve 25 securely remains in the closed position, with the additional consequence that no liquid drips. That means that both the embodiment of the valve disk 71 of the inlet valve as well as also the design of the outlet valve, in particular with respect to the spring element 35, which presses against the valve disk from below, it is ensured that no liquid drips after a discharge operation.

FIG. 4 shows the second embodiment of a pump device with an outlet valve as a disk valve. FIG. 5 shows an additional embodiment of the pump device according to FIG. 4. In this connection in the following the reference numbers from FIG. 5, when they relate to the same objects, will be included. The outlet valve 125, 225 possesses a valve body 126, 226, wherein the valve body can be clipped and arranged in the outlet spout 20 of the bellows 10. To this end the output spout 20 exhibits a circumferential collar 21 on the interior, which engages in a corresponding circumferential groove 126 a, 226 a of the valve body 126, 226. The valve body possesses an outlet spout 132, 232 wherein in the region of the outlet connector 20 the spout shows a neck 130, 230, upon whose end the valve disk labeled 128, 228 as a whole is arranged. The valve disk 128, 228 exhibits a base 128 a, 228 a roughly at a right angle to the central longitudinal axis of the valve body, at which the circumferential sealing lip 129, 229 aligns itself, said sealing lip being in contact with the inside wall of the outlet connector 20, as arises in view of FIG. 4 and FIG. 5. The valve disk is thus constructed somewhat mushroom shaped in section. In the region of the neck 130, 230 there is a radially oriented opening 131, 231 which is connected to the outlet spout 132, 232.

The valve body 126, 226 in addition shows the protrusion 135, 235 which can be held by the catcher clamp of the dispensing device.

In contrast to FIG. 4, FIG. 5 shows an embodiment of a pump device in which the valve ceiling 61 of the valve cover 60 is discharged in cascading manner in the direction of the bellows. This measure lessens the dead space in the bellows chamber 10 a, said bellows chamber being formed by the bellows 10. Through a lessening of the dead space the vacuum increases in the case of other wise equal geometrical dimensions. The arrangement of the annular nose 61 on the underside serves the same objective, that is, the side of the valve ceiling 61 facing the bellows 10. This annular circumferential nose 62 is constructed roughly triangular in cross-section and exhibits a radial distance to the valve disk 71. The arrangement of the annular circumferential nose 62 is such that it does not come into contact with the bellows 10 in case of the compression of the bellows. The triangular construction of the nose 62 in cross-section serves the same purpose.

In addition the annular, circumferential nose has the task of conducting the product delivered in the bellows chamber 10 a, e.g. a liquid soap, to the region of the center of the bellows chamber 10 a.

A further difference lies in the construction of the outlet valve 225. The outlet valve 225 shows a tangential circumferential groove 236 directly in transition from the valve body 226 to the valve disk 228 which causes the circular sealing lip 229 to swivel in the direction of the arrow 240 with relatively little resistance in the case of the compression of the bellows 10, and thus release the preparation through the opening 231 in the neck 230.

The outlet valve 125, 225 constructed as a disk valve functions in the following manner:

If the bellows 10 is compressed, that is, if the volume in the bellows chamber 10 a is decreased, then the medium located in the bellows chamber 10 a swivels the circumferential sealing lip in the direction of the arrow 140, 240 and thus releases a gap through which the medium, e.g. the liquid soap, reaches the outlet spout 132 through the opening 132, 232 in order to be removed at the end of the outlet spout. In the relaxed state of the bellows, as shown in FIG. 4, the circumferential sealing lip 129, 229 abuts on the inside wall of the outlet connector 20. The sealing lip 129, 229 in this connection abuts at an angle to the inside wall of the outlet connector on the wall of the outlet connector, to be precise in particular at an angle of 45°. 

1. A pump device for a container for liquid, pasty or foamable skin care preparations, wherein the pump device comprises: a conically tapering bellows which comprises a plurality of bellows elements each bellows element having a different diameter, wherein at least one smaller bellows element is configured so as to be capable of being pushed into an adjacent, larger bellows element.
 2. The pump device according to claim 1, wherein at least one of said bellows elements is lockably engagable with another one of the bellows elements.
 3. The pump device according to claim 1, wherein the bellows elements exhibit a cascading course in section.
 4. The pump device according to claim 1, wherein each bellows element comprises an annular base element and an annular wall element connected thereto by an annular film hinge.
 5. The pump device according to claim 4, wherein the width of the annular base element is greater than the sum of the thickness of the annular base element and the annular wall element.
 6. The pump device according to claim 4, wherein the annular base element is at an angle of >90° but <180° to the annular wall element in the initial state of the bellows chamber.
 7. The pump device according to claim 1, further including an inlet and an outlet valve.
 8. The pump device according to claim 7, further including a valve cover on an inlet side of said pump, which is connected to the bellows, wherein the valve cover bears the inlet valve.
 9. The pump device according to claim 8, wherein the inlet valve comprises a valve disk which is pressed against a valve seat in the valve cover by a spring element.
 10. The pump device according to claim 7, wherein the outlet valve comprises a disk valve which is disposed in a liquid tight arrangement in an outlet connector of the bellows.
 11. The pump device according to claim 11, wherein the outlet valve includes a valve body, wherein the valve body receives a valve disk through a neck member disposed at a distance from the valve body said valve disk abutting on the outlet connector in radially moveable fashion.
 12. The pump device according to claim 11, wherein the valve disk includes a circumferential sealing lip which is arranged on the neck so as to run diagonally in the direction of the outlet connector.
 13. The pump device according to claim 11, wherein the valve body is configured so as to be clipped and received by the outlet connector.
 14. The pump device according to claim 11, wherein the neck includes a circumferential groove in the transition to the valve disk so as to facilitate the lateral folding of the sealing lip.
 15. The pump device according to claim 4, wherein the base element and/or the wall element are constructed so as to have a cross-section which is ring-shaped, diamond-shaped, square, or rectangular.
 16. The pump device according to claim 4, wherein the film hinge film hinge, when in an extended state, connects the wall and base element of the bellows chamber via the shortest distance.
 17. The pump device according to claim 4, wherein the radial distance of two adjacent wall elements corresponds generally to the cross-section of the annular base element.
 18. The pump device according to claim 8, wherein the valve cover includes an annular circumferential nose on its side facing the bellows.
 19. The pump device according to claim 18, wherein the nose defines a radial distance to the valve disk of the inlet valve.
 20. The pump device according claim 8, wherein the valve cover defines a valve ceiling which receives the inlet valve and which is discharged in cascading manner in the direction to the bellows so as to thereby minimize the dead space in the bellows chamber formed by the bellows. 